Electronic control system



Feb. 21, 1961 AlKEN 2,972,703

ELECTRONIC CONTROL SYSTEM Filed July 30, 1957 SCAN ROLL 36 2s LENS SYSTEM &4

(SCAN ROLL 6 INPUT SIG. you

INVENTOR. WILLIAM R053 AIKEN yj fi A TTY.

ELECTRONIC coNTRoL SYSTEM William Ross Aiken, Los Altos, Califi, assignor, by mesne assignments, to Kaiser Industries Corporation, a corporation of Nevada Filed July 30, 1957, Ser. No. 675,084

4 Claims. (Cl. 315-) described in applicants copending applications, Serial No. 396,120, now Patent No. 2,795,731, filed December 4,

1953, and Serial No. 494,386, now Patent No. 2,880,341, filed March 14, 1955.

It is a particular object of the present invention to provide a control system for applying light signals to .successive intervals of a predetermined light responsive device for control purposes, and particularly for the purpose of controlling the presentation of information on display apparatus.

It is a specific object of the invention to provide a novel :system of such type for controlling the application of signal voltages sequentially to the deflection elements of :a cathode ray tube, and particularly of a thin cathode ray tube of the type set forth in the above identified dis- :closures. A further object of the invention is to provide an arrangement of the novel type for providing a direct display with a facsimile type tube.

The invention basically comprises a pulse delay line disposed in adjacent series-connected relation With a strip of electroluminescent phosphor material. A signal generating source is connected to selectively apply signal pulses to the pulse delay line to control same to cyclically energize successive incremental areas of the phosphor material. In one embodiment the generated light output of the arrangement is utilized to effect cyclic energization of the deflection elements of a thin cathode ray tube. In such arrangement a set of photoconductor elements are electrically coupled to a potential source and the deflection elements of the thin tube, and are physically disposed adjacent the strip of electroluminescent phosphor material of the light generating arrangement. As the light is emitted at successive intervals of the phosphor strip, successive portions of each of the photoconductor elements are struck by the light output and the electrical resistance characteristics of the individual photoconductor elements are varied in accordance therewith. As an increased amount of light strikes one of the photoconductor elements, the resistance thereof is correspondingly decreased and the voltage appearing on the associated deflection plate is likewise decreased. Thus as the light impulse travels across each of the photoconductor elements connected to the deflection elements of the thin tube, the electron beam of the tube is deflected into registration with correspondingly different intervals of the asl .the electroluminescent phosphor material is utilized to provide the line scan for a facsimile tube, the variable disjplay being accomplished by modulating the electroluminescent phosphor material in accordance with the nature of the incoming signal as the pulse advances along the length thereof. The manner in which the novel light generating arrangement may be utilized with other types of cathode ray tubes, including solid state tubes, will be obvious from the following description.

The invention will be understood from a reading of the following description when taken in conjunction with the drawings in which:

Figure 1 is a diagrammatic illustration of the novel light generating control system employed to energize the deflection elements of a cathode ray tube of the facsimile type; and

Figure 2 is a diagrammatic illustration of the novel light generating control system as used to eifect a direct display in a facsimile type tube.

For purposes of illustration, the instant novel control circuit is first shown in connection with a cathode ray tube of the facsimile type shown and described in applicants copending application, Serial No. 494,386, now Patent No. 2,880,341. The tube comprises an envelope 10 having an electron gun 12 disposed at one end thereof and adapted to deliver a beam of electrons 14 along a path toward the opposite end of the tube envelope. A phosphor target screen 16 is disposed within the envelope 10 in a plane generally parallel with the initial path'of the electron beam 14. An array of deflection elements 18 is disposed in spaced and coextensive relation with respect to the target 16. Each of the deflection electrodes 18 is connected to ground through respective photoconductors 20. A source of B+ voltage is suitably connected to the deflection electrodes 18 through charging resistors 22 and connected between the photoconductors 20 and the deflection electrodes 18.

The photoconductors 20 are formed of material, 'the resistance of which varies in accordance with the impingement thereon of electromagnetic radiation such as for example light. Normally, when no appreciable amount of light is caused to fall on the photoconductors 20, the resistance to the flow of electrical current therethroughis high. However, when light is caused to impinge on the photoconductors 20 their resistance characteristics change and they become more conductive or in other words the resistance to the flow of electrical current decreases.

A pulse delay line circuit is adapted to be disposed in close proximity with the photoconductors 20. The circuit comprises a power supply 24, an electrically conductive optically transparent plate 26 having an electroluminescent phosphor layer 28 disposed on one surface thereof, a matching resistor 32 and a pulse line 30 disposed in coextensive and proximate relation with respect to the electroluminescent phosphor layer 28. The plate 26 is formed of a transparent material, such as tin oxide, which is electrically conductive and at the same time allows the passage of any light emitted from the phosphor layer 28 to pass therethrough. The coil 30 and conductive plate 26 which are disposed in spaced adjacent relation constitute the two conductors of a delay line of the distributed constant type.

In operation, it is desired to sequentially energize the deflection electrodes 18 of the tube 10 such that deflecting forces may be applied to the electron beam 14 to deflect same into registration with the phosphor target screen 16. Initially, the photoconductors 20 are at their maximum resistance value thus allowing the B+ voltage source to fully charge the deflection electrodes .18. In actual practice the deflection electrodes 18 and the target screen 16 are maintained in the order of 10 kv. .thus presenting a fieldfree region therebetween enabling the .electron beam 14 to travel unafilected therethrough until such time as it sees a negative or repelling field which is estab- 3 lished by discharging or lowering the voltage on one or more of the deflection electrodes 18. Accordingly, in order to commencethe discharge cycle of the tube, the

pulse delay line 26, 30 is energized by a suitable pulse of electrical energy from the power supply 24 which energy pulse will travel along the line 26, 30 tothereby establish a field which will induce a current flow in incremental portions of the electroluminescent phosphor layer 28. The induced current established thereby effectively energizes the phosphor material of the layer 28 resulting in the emission of light therefrom in the various excited portions. The light thus emitted will effectively impinge on the photoconductors 20 in a sequential fashion causing them to lower their resistance such that the potential on the deflection elements of the tube will decrease in a negative direction. By decreasing the voltage of the deflection elements 18 in this manner, a repelling or deflecting field with respect to the electron beam 14 is established which will cause the beam 1 to be deflected toward and into registration with the target screen 16.

' along the delay length of the line 26, 30, the deflection elements 18 will be sequentially discharged defining a single line scan on the phosphor target screen 16 of the tube 10. After the pulse has travelled the'length of the delay line 26, 3t) and has effectively controlled deflection of the beam into registration with said increment of the target screen 16, the deflection elements 18 are all returned to their initially charged state through their respective charging resistors 22. This is accomplished due to the fact that when no light falls on the photoconductors their resistance to the flow of electric current is such that they will militate against the passage of any current therethrough. In order to again scan the target screen 16 with the beam 14, another pulse is delivered along the delay line 26, 30 and the action described above is once again repeated.

In its application with a conventional facsimile system, the target screen 16 is disposed adjacent a lens system 34 and a scanning roll 36. The incoming signals are applied to the cathode or control grid of the electron gun 12 according to conventional practice, whereby the electron beam 14 in its scan effects the display of the incoming signals along successive intervals of a linear path on the target. Each pulse is applied to the delay line 26, 39 in synchronized relation with the incoming signals to establish a display of the transmitted information. The lens of the system 34 directs the successive line displays into registration with the moving scan roll 36 for reproduction purposes in accordance with established practices. That is, each linear signal display of the phosphor target 16 forms one horizontal component of a pictorial representation, and a plurality of such linear representations are successively registered on the moving scan roll to form a complete pictorial representation. In this manner the novel light generating device is utilized to control a beam in the cyclic presentation of linear displays on a phosphor target for reproduction purposes.

The novel light generating arrangement may also be utilized with a conventional lens system and a scanning roll to provide a direct display in the manner of a facsimile tube. More specifically, as shown in Figure 2, the light generating structure comprised of the delay line 26, 30 including electroluminescent phosphor material 28 are coupled to a power supply 24 over conductors 38, 40, for energization thereby in the manner set forth relative to their use in the above described facsimile tube. The incoming message impulses are impressed on a suitable modulating circuit 42 which effects application of a voltage signal proportional to the value of the input signal over conductor 44 for application to the phosphor layer 28 to thereby vary the light output thereof in accordance with the variation of the input signal. It will be apparent that with the absence of an input signal for the device, the display presented on the phosphor target with the application of each pulse to pulse delay line 26, 30 will be a straight line of uniform intensity. However, with the receipt of the incoming signal, modulator 42 effects the application of biassing voltages of correspondingly different values to target 28 as each successive interval of the linear trace is effected by the applied pulse, and a direct display of information represented by the input signals is provided thereon. Representations which appear on the phosphor target 23 are directed over the associated lens system 34 to the light sensitive material on a scanning roll according to the conventional facsimile system practice described above. Since the pulse applied by power supply line 24 to the pulse delay line 26, 30 is synchronized to the receipt of the first signal for each successive line scan, the transmitted picture is reproduced as each of the successive lines is traced.

The manner in which such arrangement can be utilized to directly provide display information with other types of display presentation devices including solid state tubes, such as taught in my copending application having Serial Nos. 528,222, now abandoned, and 544,919, which were filed on August 15, 1955, and November 4, 1955, respectively, and other forms of electronic apparatus, such as for example the single or double bend thin'cathode ray tubes of the type described in applicants copending application Serial No. 396,120, now Patent No. 2,795,731, which was filed December 4, 1953, will be apparent to parties skilled in the art.

According to the provisions of the patent statutes, the principles and mode of operation of the invention have been explained, illustrated and described in what is com sidered to be the best embodiments. However, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than specifically illustrated and described.

What is claimed ist 1. A control circuit for selectively varying the value of voltage signals applied to a deflection plate for an electron beam of an associated electron tube to thereby vary the extent of beam deflection effected by said deflection plate, means comprising at least one radiation responsive element operative to offer a variable resistance to the flow of electrical current thereover responsive to the application of different light intensities thereto, means for. applying a variable light intensity to said radiation responsive element including field responsive means having an electroluminescent phosphor element disposed adjacent said radiation responsive element, field producing means for successively energizing different incremental portions of said field responsive means to effect a corresponding increase in intensity of the light applied to said radiation responsive element by said phosphor element and a corresponding decrease in the resistance of said radiation responsive element, and means for coupling an energizing circuit including said radiation responsive element to said deflection plate, whereby progressive changes in the resistance of said radiation responsive element provides progressive changes in the voltage applied to said deflection plate and a corresponding variation in deflection force applied to said beam to thereby correspondingly vary the point of registration of said beam with its target.

2. A display means comprising in combination a cathode ray tube having a display target, an electron beam source for delivering an electron beam in spaced, substantially parallel relation with said target, and a plurality of deflection plates disposed along the beam path for bending said beam selectively from different points on said path into registration with different points on said target, and means for selectively energizing said deflection plates comprising a plurality of photocell members, each of which is operative to offer a variable resistance to the flow of electrical current thereover responsive to the application of different light intensities thereto, means'for applying a variable light intensity to said photocell members including an electroluminescent phosphor element disposed adjacent each of said photocell members, and field producing means including a delay line for successively energizing diflerent incremental portions of said phosphor element to successively efiect a corresponding increase in intensity of the light applied to the successive ones of said photocell members and a corresponding decrease in the resistance in a given sequence, and means for coupling each of said photocell members in an energizing circuit for one of said deflection plates, each different photocell member being connected to a ditferent one of the deflection plates, whereby a change in resistance of the successive ones of said photocell members provides a change in the voltage applied to the successive ones of said deflection plates, and a moving field for said beam to provide a line trace on said target.

3. A display means comprising in combination, a cathode ray tube having a display target, an electron beam source for providing an electron beam, and a plurality of deflection plates disposed along the beam path for deflecting same selectively into registration with different points on said target, and means for selectively energizing said deflection plates comprising a plurality of light responsive members, each of which is operative to ofier a variable resistance to the flow of electrical current thereover responsive to the application of diflerent light intensities thereto, means for applying a variable light intensity to said light-responsive members to eflect a corresponding change in the resistance thereof, and means for coupling each of said light-responsive members in an energizing circuit for one of said deflection plates, each different light responsive member being connected to a diflerent one of said deflection plates, whereby a change in resistance of the dififerent ones of said light-responsive members provides a change in the voltage applied to the different ones of said deflection plates, and a moving field for controlling the beam to provide a line trace on said target.

4. In a display arrangement including a cathode ray tube having an electron beam source for delivering a beam along a predetermined path adjacent a plurality of deflection plates arranged in a predetermined sequence, switching means comprised only of solid state elements for cyclically energizing said deflection plates in a given pattern including a plurality of control circuits, each control circuit being connected to control the voltage supplied to a different one of said deflection plates, a plurality of light responsive members, each of which is operative to ofier a variable resistance to the flow of electrical current thereover responsive to the application of different light intensities thereto, means for applying a variable light intensity to said light responsive members to eflfect a corresponding change in the resistance thereof including an electroluminescent phosphor element disposed adjacent each of said light responsive members, and field producing means including a delay line for successively energizing different incremental por tions of said phosphor element to provide a moving spot of light therealong to sequentially illuminate the different light responsive members and to effect a corresponding decrease in the resistance of each light responsive member in sequence, and means for coupling each of said light responsive members in a different one of said control circuits to vary the voltage in the different control circuits in a corresponding sequence.

References Cited in the file of this patent UNITED STATES PATENTS 2,313,286 Okolicsanyi Mar. 9, 1943 2,684,450 "Mager July 20, 1954 2,728,021 Blanks Dec. 20, 1955 2,851,634- =Kazan Sept. 9, 1958 2,885,595 Gabor May 5, 1959 

